Pressure retaining valves of this type are in the prior art. In conjunction with hydraulic actuators in the form of load-lifting power cylinders, such valves also are referred to as counterbalance valves in technical terminology. Load-lifting power cylinders are frequently used in tools and equipment, also in the form of mobile devices such as excavators, forklifts and the like. Typically in such cases, an operator can control the pressure retaining valve by manual actuation of a control valve device. To prevent operating errors on the part of the staff in doing so, and preclude resulting hazards for both the equipment as well as for persons to the extent possible, due care shall be taken to ensure that the handling operations for the staff are simple and clear.